Next up on the schedule is Dan Lisko. His presentation is entitled "Probiotic Effect On Gastrointestinal
Microbial Community Structure and
Cortisol Production"
Dan has provided the following relevant background readings for his talk:
See you on Friday!
Dan is working on a few projects looking at the microbiome of the gastrointestinal tract, its effect on our health, and our dietary effects on its composition. His talk focused on a study he did which looked at the effects of eating probiotics (in this case, yogurt containing live cultures of bacteria) on the microbial diversity and composition. Subjects would consume 250g of yogurt every day for 6 weeks, and once a week would submit a stool sample. Bacterial DNA would be isolated and used to characterize the composition of the gut microbiome using quantitative PCR technology. The weekly DNA samples would be compared to each subject's baseline stool sample DNA (taken before the yogurt regimen began) in order to track changes. The results showed increases in microbial diversity, as well as increases in bacterial strains considered beneficial to our digestion and overall gastrointestinal health. The information gained in these studies could help develop treatment plans and diets for patients with certain gastrointestinal disorders.
ReplyDeleteSpeculate on some of the mechanisms by which our gut microbiome may affect our digestive health. What other areas in our bodies are normally colonized by characteristic microbial flora?
Dan's presentation was a great look into the complexity and dynamic nature of the human gut microbiome. I am interested to here how the results of his latest study turn out and whether or not the microbial community shows direct correlations with cortisol levels.
ReplyDeleteThe mouth is a source of characteristic microbial flora including streptococci among many others genera. Many of these bacteria are potential sources of mouth infections and dental issues when the conditions are right.
Dan you did a great job presenting and explained everything very well!
ReplyDeleteThe lung microbiome contains normal bacterial flora including 9 major bacterial genera that help remove bacteria in the upper and lower respiratory tract. However in immunocompromised individuals some of the normal biota can lead to respiratory diseases such as Neisseria meningitidis (meningitis).
Very well-given presentation Dan.
ReplyDeleteThe vagina definitely has its own little microbiome. The major organism found is Lactobacillus, which ferments carbohydrates to lactic acid. This keeps the pH of the vagina low, creating an enviroment that is too acidic for most pathogens. The composition of the vagina's microbiome is affected by sexual activity and can vary during menstrual cycles.
As Dan pointed out in his presentation, microbes in the gut can help us breakdown foods that otherwise our digestive enzymes alone could not breakdown (ie. plant products). In a healthy and diverse microbiome this can lead to an abundance of nutrients that can go on to be precursors for necessary biomolecules such as amino acids, vitamins, and hormones. So instead of taking a multi-vitamin supplement which may be poorly absorbed by the body to bolster nutrient intake, one could focus on building up a diverse microbiome.
ReplyDeleteAnother "ecological niche" for microbes is the skin, which in and of itself is highly diverse due to the sheer size and variation of this organ. For example, micro-organisms found on your hands (constantly dry and exposed) will be different than those in your armpit (moist, dark). The skin also has an array of immunological functions that influence the microbiota composotion.
The Human Microbiome Project has made a huge advancement in the identification of microbial communities within the gut, mouth, skin, nose and urogenital tract. However, some areas of the body have remained less popular when evaluating their micro biome. One such area is the surface of the eye. Dr.Shestopalov and his team found that a dozen bacterial genera dominate the conjuctiva of the eye. The corneal surface also contained about a dozen different genera. Most of these bacteria have not been classified yet. Dr.Shestopalov also found that people can have a huge variation of microflora and still have healthy eyes. They also found that people with keratitis infections lacked about half the amount of microflora present in a healthy eye.
ReplyDeleteChristine pointed out that the nose has its own unique microbial community. This community is comprised mostly of Staphylococcus epidermidis and Corynebacterium, but can also harbor pathogens like Staphylococcus pneumoniae or Haemphilus influenzae. Due to connections with nasal passages, pathogens can spread to the middle ear or to the lower respiratory tract, as Gabriella mentioned.
DeleteThere ia paper that talked about how gut microbiome could initiate Inflammatory bowel diseases (IBD), consisting of Crohn's disease and ulcerative colitis. These bacteria genera (Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria) confers health benefit to human under normal condition, but when they are functionally altered they can lead to IBD. read more on http://www.nature.com/ajgsup/journal/v1/n1/full/ajgsup20124a.html
ReplyDeleteOur eyes (conjuctiva) are colonized by coagulase negative Staphylococci, Haemophilus spp., Streptococci, Staph. aureus etc.
Dan's study is a complex but easy to relate to concept that I am interested to see the results of. Relating the creation of stress to microbial diversity in our bodies is a unique and fascinating subject. It seems like there will be a great deal of variables to consider (diet, gender, age, weight) which makes the pending results even more interesting to see.
ReplyDeleteHundreds of genera of bacteria make their home on human skin, often relying on sweat and oil glands for nutrition. Despite usually being relatively harmless, open wounds are an invitation for these skin bacteria to cause infection.
Commensal bacteria of the skin and mucosa can certainly be important in the activation of both the innate and adaptive immunity. Hosts must maintain proper tolerance in response to bacterial populations to prevent extended stimulation of the immune system and subsequent inflammation. Similar to what Dan talked about with C. difficile infections in the gut following antibiotic treatments, disruptions in mucosal microenvironment can alter populations and potentially lead to opportunistic infections.
ReplyDeleteOverall, the gut microbiome seems to be a really interesting topic with a lot of potential for new discoveries, especially when only about 50% of the bacteria in the gut can be cultured with conventional techniques due to close co-evolution of the bacteria with the host.
Dan's présentation was a good study on how diet and the bacterial biome that lives in the gut can be beneficial.
ReplyDeleteAnother area would be the ear. There has been research done on infants to see how good bacteria could help with reoccurring ear infections. The doctors gave the children antibiotics to kill the infection (as well as the good bacteria) in the affected area and then inoculated them with alpha-streptococci, a good bacteria. The experimental group showed a much lower number of reoccurrence in comparison to the placebo control group.
A common place to have normal bacterial flora is within the urogenital tract. It contains Staphylococcis epidermidis and Enterococcis faecalis. During urination, most of this flora is flushed out. This makes it very difficult for the establishment of bacteria within the tract.
ReplyDeleteI think one of the most interesting facts is that Methicillin-resistant Staphylococcus aureus (MRSA) is present on almost everyones skin surface. For those who do not know, this can cause massive systemic infections that are resistant to the antibiotics typically used as treatment. This bacteria can enter through the skin, and if not treated quickly can lead to life threatening infections in the bones, joints, the bloodstream, heart valves and lungs. This typically only occurs in those who are weakened by hospitalization or are immunocompromised. Individuals who are healthy rarely succumb to the infection. This illustrates just how delicate the balance is between us and the organisms we play host to.
ReplyDeleteYou guys are really making this blog experiment a success! Thanks for your contributions!!!
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